accelerated diazo feinting and ma-



Reissued Apr. 26, -193:8

PATENT OFFICE ACCELERATED DIAZO PRINTING AND. MA-

. TERIALS THEREFOR Walker M. Hinman, Winnetka,'Ill., assignor to The Frederick Post Company, Chicago, 111., a

. corporation of Illinois No Drawing. Original No. 2,027,229, dated January 7, 1936, Serial No. 549,561, July 8, 1931.

plication for reissue February 19, 1938, Serial 7 22 Claims.

The present invention relates to light-sensitive materials, to products incorporating light-sensitive materials, and to methods of using. such materials and products. It has special reference to photographic work, especially in the field of technical copying which is exemplified by the so-called blue print, brown print, and diazo type processes and papers.

The invention may be used in other fields as will appear hereinafter, but at present it has its chief utility in this field as a substitutep process and product for the present day usages of technical copy papers such as sensitized diazo papers andthe well known blue print papers.

The blue print papers ofier a limited utility, being' confined to blue and white contrasts. They print negative, that is, a tracing having an opaque dark line on a white translucent or transparentbackground, produces a white line on a blue background. Other disadvantages of the blue print papers are 'well known.

The diazo papers 'ofier a wider variety of color and they print positive. In them a compound is used which is sensitive to light so that light decomposes it. When and where the sensitive compound is not decomposed, the treatment following light exposure causes the sensitive compound to be developed into a dyestuil.- Accordingly the dyestufi is formed where the paper is screened from light and a direct print results; The nature of the light-sensitive compound will be explained more in detail hereinafter, so it will suffice for the present to term it by its true technical name a diazonium compound, also called a "diazo compound. Certain oi the dyestuffs, called azo dyes, are made .from a diazonium compound by a coupling reaction with a color-forming component. Diazonium compounds are characterized by instability, which property varies from explosive instability to high stability. The degree of stability is dependent upon the nature of the nucleus of the compound *as well as upon the conditions to which it is exposed. Heat, light, acidity, alkalinity, pressure, and associated substances also determine stability. Diazo papers utilize these diazonium compounds having instability to light.

placed in situ on paper and be there dried and retained as sumciently stable compounds until requirements.

they are used in commercial, reproduction by light-printing.

The art has been able to select only a few specific substances which are practical and successful for commercial use. There are conflicting properties to be considered. On one hand the .diazonium compound must be sufiiciently unstable to lightso that a print can be made at commercial speeds which are well established in the art. On the other hand it must be sufliciently stable so that it can be prepared, applied to paper, dried thereon stored, shipped, again stored, opened, handled in preparation for exposure, and then exposed to give clear and sharp prints. These are the rigid requirements of commerce, and many incidental factors must be considered, such'as light, heat, cold, moisture,

-etc. There must also be considered the permanence of the color formed. As a consequence the art has had difiiculty in meeting all the practical requirements. Too stable compounds could not be used, and too unstable compounds ducing results on exercise of unusual precautions, but they. will not meet the commercial Many patents will be found which aredirected to specific bases or classes of bases, bu commercial success with them is not assured. a

By use of the present invention the diazonium compounds may be selected particularly for their high stability without that other consider :ation of a special "degree of instability which renders them useful for commercial speeds of light-printing and as marketable products.

compounds- Another object of the invention is theforma tion of an accelerator in situby the action of the light which is to effect the decomposition of the diazoniumv compoimd. Other objects of the invention relate todevelopment of the dyestufl" from the undecomposed diazonium compound, and the development of the dyestuif with special regard for avoiding certain possible defects which may arise from material associated with theaccelerator.

In general the objects are to develop the dyestufl' in a manner which is compatible with all.

the conditions which prevail, as will be more clearly explained hereinafter.

Various other and ancillary objects and advantagesof the invention will be apparent from the following description of the invention and from the several accompanying examples.

It is known that diazonium compounds are.

particularly sensitive to certain other substances which act as accelerators or catalyzers of decomposition. In Perkin and Kipping, Organic Chemistry Ed. of 1911, page 414, it is stated: The diazoniu'm salts behave in a very remarkable way when they are treated with cuprous salts; when, for example, a solution of phenyldiazonium chloride is warmed with a solution of cuprous chloride in hydrochloric acid, nitrogen is evolved, but instead of phenol, chlorobenzene is produced. In this reaction the diazonium salt combines with the cuprous chloride to form a brownish additive compound, which is decomposed at higher temperatures.

The article continues showing that cuprous bromide and potassium cuprous cyanide react similarly. v It is also shown on page 416 that copper powder effects the decomposition of diazonium salts.

Copper and its cuprous compounds are therefore old and well known examples of accelerators light, such as ammonium ferric oxalate (known also as ammonium ferrioxalate) of the blue print art, so that they are activated to produce an accelerator which speeds up the decomposition of the diazonium compound. I do not state that all substances which are light-sensitive will produce accelerators for this inventiomand I have found that some will function readily with-certain diazonium compounds and appear not to function, or to be of little advantage when used with other diazonium compounds. compounds and copper compounds of certain type sometimes act equally on certain diazonium compounds, and on other ones they showlittle beneficial effect, or one is beneficial and the other appears to have little accelerating efiect, or may even be injurious. Among other light-sensitive in U. S. Patent No. 1,594,470.

Present day blue print practice has set the standard for degree of light exposure acceptable to the art. The present invention in its preferred form makes use of two classes of sensitive substances, one of which is adopted from the" blue print art, and which is sufliciently speedy in response to light. The other is adopted from the diazo art and is the preferred species within which may be classed those defined as too stable for practicaluseinthediazoart. 'I'heflrst'reaction forms a product which is an accelerator to speed up the second reacidon to a commercial speed.

Inorder tobespeciflcforthew mfieofflimtration, a generalized example will be stated.

For example, chromium Example I g Cresidine is diazotized to form a diazonium I compound which may be dried in a suitable coating on paper in a manner well known in the art. The diazonium compound is relatively stable against light and hence is not commercially desirable in the heretofore known uses, as its printdiscovered that the ferrous compound accelerates the decomposition of the diazonium compound.

It is analogous to the action of the cuprous salts above referred to, but it is entirely unexpected i that the accelerating efiect should occur in a dried mixture.

Both the diazonium compound and the ferric oxalate alone, and combined, and in the dark, are

highly stable and easily meet the practical requirements of the art to place them on the paper and to get them into the hands of the user with no more precautions than are required for ordinary blue print papers.

The light-struck portions: of sensitized paper should lack a diazonium compound which'can be coupled with a dye-forming component. I may have such a component present in the paper so that the-pap r. may be subjected to conditions favoring the coupling,.or I may apply the component to the light-printed sheet and thus develop the color. .This latter. method is preferred, because the component may be varied according to the color desired.

Thus, I maywet the. dry exposed sheet, as with a sponge which is wet with a solution containing a coupling component, such as beta naphthol in sodium hydroxide, or resorcinol' in sodium hydroxide. Other coupling agents may; be used such as phloroglucin, II-acid, gamma-acid, J- 4 'acid, 2-hydroxy B-naphthoic acid,

metal from the accelerator may incidentally act 1 as a mordant for the dye.

Because metal salts, such as iron salts from the accelerator may be present, care must be taken to prevent coloration of a dmired white field.

Ferrous iron compounds in particular may slowly oxidize and cause a brownish color in the field, which would otherwise be white; Therefore, where such tendency exists, I use a cleaning agent which insures removal of such iron compounds.

or any other coloringagent. This is preferably,

although not necessarily, incorporated in the solution containing'the couplingcomponentp Both R-acid, or

' anisidine and para phenetidine,

the oxygen in effecting reduction.

some

The diazonium compound I have found that those amino compounds are suitable which can be diazotized to form very stable diazonium compounds. Of course, I prefer the more highly stable ones to take full advantage of the invention. I have found that various aniline derivatives may be used, especially ortho Benzidine may be used, but it is less suitable and not satisfactory for the more severe commercial demands. Tolidine isbetter than benzidine, and dianisidine is still better. The amino derivatives of napthalene, anthracene, carbazol, diphenyl amine, and others may be used. The stability follows the general rule of the dyestuff art, that stability increases with the complexity of the molecule, and that the substituent groups have certain characteristic influences dependent upon their character, their positions in the nucleus, and their relations to other substituents. In general I have found that the methoxy and homologous groups produce stability, especially when one is adjacent the amino group. The following amines are listed as suitable; and selection from them may be made for stability without the consideration of suitable light sensitivity when used alone:

Para amino acetanilide, para amino acetophe none, l-amino anthraquinone, para amino dimethyl aniline, para amino diphenyl, para amino diphenyl amine, amino G-acid, ortho anisidine, benzidine, para chloro ortho anisidine, cre'sidine, dianisidine, dichloro aniline, beta naphthylamine, tolidine, para toluidine, para phenetidine, xylidine.

The accelerator The accelerator per se is preferably not to be present with the diazonium compound or to be active, except by action of light as in printing. It is to be formed or activated by the light. The form of ferric oxalate used in blue print papers is suitable. Uranium, chromium, copper, cobalt, nickel and manganese are other metals like iron which have higher and lower oxides. These may be used, but all salts of these metals are not usable, nor are these metals universally useful with all diazonium compounds, as explained above, and as will appear below. Certain salts of the higher oxides are light-sensitive and form the lower oxides. Citrates, tartrates or oxalates may be used. or other metal to be added as a specific salt such as the metal tartrate, citrate or' oxalate. It is suilicient that the metal ions be present and that the acid ions or other material be present so that it maybe oxidized as the reduction occurs. An oxalate is the preferred salt used for consuming The lower oxide forms, as in salts, appear to be active. A

metal itself obtained by light-reduction from a salt, such as a silver'halide may also be effective.

As a result of many experiments with many materials I find that an iron compound is most universally effective. It is my opinion, not fully confirmed. that of those metals having higher and lower oxide forms, the activity as accelerators is greatest with those metals which normally exist or tend to exist in the higher oxide form. This is a very characteristic property of iron which has the ferric and ferrous forms; of chromium, which has the chromic and chromium forms; and of copper. "which has the cupric and cum-nus forms. These metal forms have their special tendencies to be converted from one fonn to another. and the facility of such conversion is de- It is not necessary for the iroh pendent, upon many factors, including acidity, alkalinity, and associated materials. Conditions prevailing in papers treated with various diazonium compounds therefore may be very efl'ective in preventing one metal from functioning properly in one case, whereas it may function excellently in another case.

It is also pointed out that it is not necessary to employ the accelerating agent in the form of a simple metal salt, like ferric chloride, cupric chloride. The metal may be present in a complex acid radicle, as I have successfully used potassium dichromate. It is well known that chromium has three valences, and three oxide forms, chromic anhydride-Cr03, chromic oxide CrzOa, and chromous hydroxide Cr (OH) 2. I have found that the best results are obtained with chromium compounds by employing chromates, and offer no theory to explain the specific mechanism of its action.

Dye-forming component The dyestufl art teaches what bases and what components combine to form certain colors. By the proper choice of components and bases, practically any color may be formed, and the manner of its'formation is easily ascertained. Where the component is applied after the printing, the field" of choice is wider than where the component is present in the paper with the diazonium coinpound. In case the component is included in the paper prior to printing, as is done in some papers,it must be compatible with the presence of the accelerator, with the material which forms the accelerator, with the products formed from the accelerator, and with practical requirements. Specific coupling components are not herein enumerated but some may be foundin the appended examples, since these are too well known in the dyestuif art.

Clean-innocent I include in the above term the material which is effective to prevent a discoloration of the field. It may be an acid, an alkali or a salt, which functions in the coupling reaction, or it may be a specially employed ingredient. In the case of ferric oxalate as the source of the accelerating substance, I use a solution of an oxalate salt such From the two foregoing paragraphs it is seen that two processes may be required after printing, one, to develop the color, and two, to purge the paper of possible discoloring material, especially from the accelerator. These may be 'com bined into one step using a solution having ingredients suitable to perform the two functions. Thus, one application of one liquid to the printed paper may be all that is required to develop a' suitable permanent and attractive contrast, after which the customary washing is made.

The

By the term can-let I refer 'to the material which carries the coating. In the art as it is developed today a paper of felted fibers is commonly employed. But I have used glass, and

other rigid substances, either transparent, translucent or opaque. Cloth or films of cellulose nitrate, cellulose acetate, regenerated cellulose, gelatine and the like may be employed. There is no essential co-action between the carrier and the film, and of course a carrier is chosen in which ingredients of the carrier do not adversely affect the sensitive composition while in storage or at any other timeprlor to actual exposure to light for printing.

Materials for the examples In the following examples, unless otherwise specified-it is to be understood that the carrier is a 50% rag stock paper. The exposures of the sensitized papers of the examples have been made under uniform, comparable conditions which are at the present day accepted as standard or commercial. These involve an arc lamp as a source of light and rotary printing machines. A common commercial exposure is about 3 minutes, but in the examples variations will be noted.

The diazotization may be carried out in numerous ways as is well known in the art, and

variations frequently depend upon the characteristics of the amino compound employed. Unlessotherwise specified the diazotiz'ations in the accompanying, examples have been carried out using the weight of amino compound specified, 40 cc. of 37% hydrochloric acid, 14.5 gms. of sodium nitrite (96%) and the necessary water. It is to be understood that the usual procedure is to dissolve the nitrite and slowly add it to a solution containing the acid and the amino base,

either solid, or dissolved, usually in the cold to preserve in solution the nitrous acid formed, and to prevent decomposition. A large or small volume of liquid may be employed and the character of the dye and desired intensity of the print in part determine the volume. Unless otherwise specified the volume of water in the diazotization may be taken as about 1 liter or 1 quart for the amountsabove given.

The following examples have been developed with a developer which, unless otherwise specified, is compounded as follows:

- V Grams Coupling ,component 10 Anhydrous potassium carbonate 14 Potassium oxalate (K2C2O4.H2O)

Water about"; 1000 In' the above formula the oxalate is present to function in removing iron residues where iron is used as the accelerator. It is not necessary for the removal of compounds of copper, chromium and other residues, as they are less colored than iron. Where it is desirable to remove residues, like copper or chromium compounds, ammonia or tri-ethanol amine may be employed. These form soluble complexes with the residues'and eflect removal from the print.

Example II.'Pora amino acetanilide Thirty grams of para amino acetanilide may be diaz'otized as above indicated using, however, about 5 liters of water. A brownish dlazo solution results which is fairly stable to storage. A paper coated with the solution, and dried requires an exposure of about 14 minutes to give good prints, and the so printed paper may be developed with beta naphthol, R-acid (beta naphthol 3-'6 disulphonic acid), J-acid (2 5 amidonaphthol-'I-mono-sulphonic acid), gamma acid (beta naphthol 6-8 disulphonic acid), resorcin, *phloroglucin, Nevile and Winthers acid There is acceleration, but it is less, and a 2.

,posure beyond 2 minutes gives little improve eifective period of acceleration is in ,the first 2.

. paper in the same-period shows but slight evi- (alpha naphthol-4-mono-sulphonic acid), H- acid (1-8-amidonaphthol-3-6-disulphonic acid), and others. The paper is stable and useful, but too slow.

To accelerate the printing speed, I add to cc. of the diazo solution as above prepared:

Gram Ferric chloride (FeC1:.6H:O) 1 Oxalic acid (112020421120) 1 Potassium oxalate (K2C2O4.H2O) 1 The modified solution may be coated onto paper and dried in the usual way. It may be printe in 2.5 minutes to produce a satisfactory contrasting print when developed with phloroglucin. Exposures of 5 minutes and 7.5 minutes improv the contrast, but the increasing improvement less than that to be expected from the increas time. Paper similarly prepared, exposed and developed with no addition of ferric chloride, as standard for comparison; gives a much inferio and an incomplete print at 7.5 minutes exposur than the, accelerated paper in 2.5 minutes. In place of using ferric chloride, the sam amount of potassium dichromate (KzCrzOv) ma be employed, but not with the same results minute exposure is about comparable to a 'l. minuteexposure of the blank. Additional'ex ment.

In the case of iron and chromium the mos minutes of exposure.

Cupric chloride substituted for the iron 0 the chromium accelerator shows little accelera tion.

The same accelerators have been found t have the same relative advantages where orth tolidine or para phenetidine are employed the amino compound.

Example [IL-Para amino acetophemme Twenty-seven grams of para amino acetophe none may bediazotized, usingabout l'liter 0 water. The diazo solution is not very stable Paper prepared from the solution may be prin v in 16 minutes exposure, and developed with nu merous coupling components including H-acid Accelerated papers may be prepared as in Example-II, using the materials and proportio therein named. The control in 6 minutes 0 exposure, developed with H-acid, shows no de composition of the dfazonium compound. 1h iron accelerated paper shows sharp contrast i the same treatment; the chromium accelerate paper shows acceleration but only partial contrast in that time; and the copper accelerat dence of acceleration.

The control sheet on development shows som bleeding of the dye, and the bleeding is no evidenced where the metal compounds hav been added. This illustrates the mordanting effect of accelerating agents.

The same order of advantage has been foun where other amino compounds are employed as in Example IX below, and also where I ha used benzldine as the amino compound. In th latter case an.18 minute exposure for an unac celerated diazo coating may be reduced to 2. minutes.

Example IV.1.-amino anthraquinone Forty-flvegrams of l-amino-anthraquinone a dlazotlzed using about 1 of water. The

amine which I employed was, difllcuit to dissolve in hydrochloric acid, even on boiling. The diazo solution contained a sediment from which a clear yellow solution wasfiltered. This may be coated on paper and even dried with heat, remaining sensitive to light, making good prints in three minutes, developed with numerous coupling agents, including H-acid.

. Iron, copper and chromium accelerated papers were made as in Example H, with a control or blank. The blank gave a good print in 3 minutes, and the iron and copper gave as good a'print in one minute, developed with H-acid. The iron and copper appear substantially equal in power in this instance, while the chromium paper showed no acceleration, and evidenced a disadvantage, apparently bleaching the compound, both where it is exposed and unexposed.

This illustrates the specificity of the combine.-

tions.

Example. V.--Para-amino' climethyl aniline Twenty-seven and a half grams of para amino dimethyl aniline are diazotized, using 70 cc. of the 3'7 hydrochloric acid, 16 grams of sodium nitrite and about 2 liters of water. A dark brown diazo solution is obtained with some sediment from which a fairly stable clear coating liquor may be filtered. development with phloroglucin makes an excellent black print.

Control and accelerated papers were made as in Example II .with copper, iron and chromium.

In a three minute exposure, the control, the iron' and the chromium papers appear nearly alike, and the copper paper appears slightly accelerated. In a 6 minute exposure all appear similar. This further illustrates the specificity of combinations.

Example VL-Para amino'cliphenyl Thirty-four grams of para amino diphenyl printed and developed with Nevile and Winthers acid makes good prints in- 16 minutes exposure. An iron accelerated paper makes a better print in three minutes than a control. Copper works.

slightly better than chromium, but both are less efficient than the iron.

In Examples II, III, and V chromium is hetter than copper, but in this example copper is better than chromium. I have also found that Where I use beta naphthylamine, copper is better than chromium, and that in the case of chromiumthere is an undesirable bleaching, as in Example IV.

' Example VII-Amino G-acid Example VIII.Dichlo1-o aniline Thirty-three grams of dichloro aniline, dis solved with 200 cc. of 37% hydrochloric acid, diazoti zed with 16 grams of sodium nitrite 'and about 800 cc. of .wate'r,'makes a paper which A six minute exposure and may be exposed for 16 minutes and developed with resorcin to form a good print. An iron accelerated paper prepared as in Example II makes a similar print in 3 minutes, during which time the control shows no contrast.

Example IX.-Ortho amino anisole Twenty-four and a half grams of ortho amino anisole is diazotized. The diazo solution is light yellow and does not noticeably decompose on storage, or upon coating paper and drying. After 16 minutes exposure and'development with beta 'naphthol, it gives a bright red print.

noticeable in the control, but in the accelerated papers it is absent.

Example X.Diam'.sidine Thirteen and eight-tenths grams of dianisidine, 22.5 cc. of 37% hydrochloric acid, 8 grams of sodium nitrite, and about 10 liters of water are used to diazotize in the usual manner. The diazo solution is very stable to storage and to boiling, and stability may be further improved by adding more acid.

A 10 minute exposure and development with 7 control in 6 minutes.

- Emample XL-Para amino diphenylamine For the p p se of illustrating another point the case of para amino diphenylamine is mentioned, not as'an example of the invention, but in explanation of an. important point in connection with it. This material forms a very stable diazo solution which can be developed to a black print by phloroglucin and to an attractive blue by H-acid. It is very light sensitive and appears to be at least as sensitive or is more sensitive than v the iron accelerator, when a paper is made and iron is incorporated as previously described. This example illustrates the fact that not every diazo solution, even though one be stable, is capable of being accelerated. by iron with oxalate. I do not state that it is incapable of acceleration, for other material or other combinations which create the accelerator more speedily might also accelerate Example XII.Pam phenetidin e Twenty-seven and a halt grams of para phenetidine are dia'zotized with about 2 liters of water;

60 grams of R-acid, as a. coupling agent are pres ent in the diazo solution, but it does not couple in the acid solution and it can be made to couple by adding alkali to the solution, or to the paper coated therewith, either before or after exposure.

Diazo papers of this type are used' extensively in.

A control and an accelerated paper may bemade from the potentially reactivedye-forming diazo solution above described by adding the ingredients in the proportions hereinabove given as generally applicable to these examples.

A control paper exposed for 3, 6 or 9 minutes showed no signs of diazo decomposition.

An iron accelerated paper showed decomposition of the diazo compound in 3 minutes ex- V was less accelerated than the iron paper in 3 i posure. A copper accelerated paper showed no more'decomposition than the blank. A chromium accelerated paper showed slight decomposition in 3 minutes, but even in 9 minutes it Example XIII.--Other combustion agents In the foregoing oxalic acid added as such or as an oxalate is the combustion agent, which is oxidized during the reduction by light of the higher oxide to a lower oxide. Citric acid and tartaric acid are also effective with iron, chromium and copper.

2-amino anisol may be diazotized to formed a 1/10 molar diazo solution in the usual way. Control and accelerated papers have been made as above described, using in the amount specified either oxalic acid, citric acid, tartaric acid, or no such acid, each case in combination with the amount specified offerric chloride, cupric chloride, potassium dichromate, or no accelerator. In the four combinations. with no organic acid (combustion agent) very. poor and indistinct prints result in a fixed time of exposure and development with Nevile and Winthers acid. In

distinct. In the four cases of copper, all prints werefaded and washed out in appearance, but those three having the acids show more clarity than the one with no acid. In the four cases of chromium, the results were better than with no metal, better than with copper, but not so good as with iron. g

This experiment further illustrates the superiority of iron, the equivalency of citric acid, tartaric acid, and oxalic acid, and the specificity of combinations.

In the foregoing experiments of this example. the developer unlessotherwise specified co ta ned 7 .pear ineffective.

10 grams of Nevile and Winthers acid and 10 grams anhydrous potassium carbonate per liter. For the iron papers, the developer had in addition 90 grams of potassium oxalate (KaCzOtiHzO) per liter. For the chromium and copper papers the potassium carbonate as the alkaline agent, and the potassium oxalate as the cleaning agent, have been replaced by the alkaline cleaning agent triethanol amine to the extent of 10 grams per liter.

Theeontrol and accelerated papers In ordinary diazotizing processes the residual I coating acid in character. In making control and accelerated papers as above described, the addition of oxalates, citrates, tartrates and the like replaces the stronger hydrochloric acid with a weaker organic acid, such as oxalic, citric or tartaric. These are less destructive and corrosive, and form a better paper for commercial use.

Although the present invention has been generally described and illustrated by reference to the printing of papers, like blue prints, usually for records and drawings, it is not limited to such a field. It may be applied to printing cloth for dress goods, household purposes and the like, for making wall papers and in any other field where dye-stuffs in design form may be desired.

Exposure for partial and complete decomposition of diazo coatings may be effected, and by development; no color, high color, and a variety of tones of color may be efl'ected at one time. Various developers can be printed onto an exposed coated or impregnated surface to give different colors in the design.

The field becomes more practical and open to such a process because more stable dyes may be used. The fact that the accelerator may mordant the dyestufi also aids in producing more stable and fast colors by the light process, than has been possible heretofore in the art.

The use of the present invention in printing cloths and papers with art designs permits elimination of plates, and rolls, out or engraved. The

,usual copper rolls used in printing textiles are "solutions in the order of addition found in the above description. I have changed the method of diazotization in numerous ways, and have added the accelerating agent,-, such as the iron compound before diazotizatiori without loss of the accelerating eflect.

. In generaL'it appears that there is an unordered specificity of materials and combinations which might be thoroughly explained as an ordered one if sufflcient combinations were studied. Iron with oxalate, appears to be most universally speciiic, and most advantageous. Copper and chromium sometimes appear fully equivalent to iron, or to each other, or one or both sometimes ap- It is to be understood that no general limitations should be placed upon any .material, and that the invention should not be limited by nor to the disclosures herein made.

The disclosure clearly teaches one skilled in the art that he may modify the combinations 20,708 ing from the spirit and scope of the invention as expressed in the appended claims.

I claim:

1. A photographic article comprising a carrier having a thin layer of material containing a light-sensitive diazonium compound and the essential component parts 0! a light-sensitive salt, one component part being a higher oxide form of. a metal having two oxide forms, and another part being organic in character and being a reducing agent under the influence of light for reducing the higher oxide form to alower oxide form, the lower oxide form serving after its formation by light team in the decomposition of the diazonium compound.

2. A photographic article comprising a carrier having a thin layer of material containing a light-sensitive diazonium compound, a compound having metal in higher oxide form selected from the group consisting of iron, chromium and copper, and a combustion agent for said form of selected metal, the metal compound and the combustion agent being reactive together under the influence of light to create an accelerating agent for the decomposition of. the diazonium compound.

3. A photographic article comprising a carrier having a thn layer of material containing a light-sensitive diaz'onium compound, a compound having metal in higher oxide form selected from the group consisting of iron, chromium and copper, and an organic combustion agent for said form of selected metal, the metal compound and the combustion agent being reactive together underthe influence of light to create an accelerating agent for the decomposition of the diasonium compound.

. 4. A photographic article comprising a carr er having a thin layer of material containing a light-sensitive diazonium compound, a compound 01' metal in a hgher oxide form selected from the group consisting of iron, chromium and copper, and a combustion agent ior said form of selected metal, said agent being selected from the group of tartaric acid, citric acid, and oxalic ac d, the metal compound and the combustionagent being reactive together under the influence of light to create an accelerating agent for the decomposition of the diazonium compound.

5. A photographic article comprising a carrier having a thin layer 01' material containing a light-sensitive diazonium compound, a ferric compound, and a combustion agent for said ferric form of iron, said ferric compound and the combustion agent being reactive together under the influence of light-to create an ac'celeratng agent for the decomposition of the diazonium compound.

6. A photographic article comprising a carrier having a thin layer of material containing a tion of the diazonium compound. a

-7. A photographic article comprising a. carrier having athin layer of material containing a light-sensitive diazonium compound; a ferric compound, and a combustion material containing an oxalate radicle, said ferric compound and the combustion material being reactive together under the influence oflight to create an accelcrating agent for the decomposition of the diazonium compound. v

8. A photographic article comprising a carrier having a thin layer of material containing a I light-sensitive diazon-Zum compound,- a cupric pric form of copper, said cupric compound and the combustion agent being reactive together under the influence of light to create an accelcrating agent for the decomposition of the diazonium compound.

9. A photographic articlelcomprising a carrier having a thin layer of material containing a light-sensitive dazonium compound, a compound containing a higher oxide form of -.chromium,v

and a combustion agent therefor, said chromium compound, and a combustion agent for said cucompound and the combustion agent being reac- I of said metal, whereby in the reduction to procontaining a 7 duce an agent eifective in the decomposition of the diazonium compound.

11. A light-sensitive material containing 2. nor- I mally slowly decomposable F light-sensitive dyeforming diazonium compound and a light-sensi V tive ferric oxalate salt, whereby on exposure to light the decomposition of ferric oxalate hastens the decomposition of the; diazonium compound.

12. A light sensitive material containing a decomposable diazonium compound incapable when decomposed of combining with a coupling agent to form a dyestufl', and accelerating material for said decomposition intimately associated with said diazonium compound, said acceleratingmaterial having a reducible substance in the form of a compound of a metal in higher oxide form selected from the group consisting of iron, copper and chromium, and a combustion substance derived from the group consisting of oxalic acid,

citric acid and tartaric acid. the combination of diazonium compound, reducible substance, ahd combustion substance being such that under the influence of light the decomposition oi the diazonium compound is hastened-by the presence of a compound having a lower oxide form of the metal, and such that under the influence of light the combustion substance reduces the higher oxide form of said metal to the eilective lower oxide form. Y

13. A light sensitive material containing a decomposable diazonium compound incapable when decomposed-oi combining wth a coupling agent to formal dyestuff, and accelerating material for said decomposition intimately associated with 3 said diazonium compound, said accelerat ng material having a reducible substance in the formj of a compound of a metal in higher oxide form selected from the group consisting or iron, copper .and chromium,vand a combust on agent for said higher oxide form of metal, the combination of diazonium compound, reducible substance and combustion; agent being such that under the influ'ence of light the decomposition is hastened by the presence of a compound having a lower oxide form of the metal, and such that under the influence of light the combustion agent reduces the higher oxide form of said metal some effective lo'wer oxide form.

14. A light sensitive material containing a decomposable diazonium compound incapable when dueible to lower oxide form, and a combustion substance derived from the group consisting of oxalic acid, citric acid, and tartaric acid, the combination of diazonium compound, reducible substance, and combustion substance being such that under the influence of light the decomposition of the diazonium, compound is hastened by the presence of a compound having a lower oxide form of the metal, and such that under the infor said decomposition intimately associated with 7 said diazonium compound, said accelerating material having a reducible substance and a bombustion agent combined together in the form of a light sensitive ferrioxalate salt reducible by light to form a compound of ferrous oxide, the combination of diazonium compound and ferrioxalate salt being such that under the influence of light the diazonium compound decomposes faster by virtue of the presence of the ferrous oxide compound formed by the effect of light.

16. A light sensitive material containing a decomposable diazonium compound incapable when decomposed of combining witha coupling agent to form a dyest'ufl, and accelerating material for said decomposition intimately associated with said diazonium compolmd, said accelerating material having a reducible substance in the form of a compound of a ferric form of iron, and a metal, andsuch that underthe influence of light the combustion'substahce reduces the higher oxide form of said metal to the efl'ective lower oxide form.

17. A light sensitive material containing a decomposable diazonium compound incapable when decomposed of combining with a coupling agent to form a dyestufi, and'accelerating material for said decomposition intimately associated with terial having a reducible substance in the form of a compound of a ferric form of iron, and a combustion agent therefor derived from the group consisting of oxalic acid, citric acid and tartaric acid, the combination of diazonium compound, reducible substance, and combustion substance being such that under theinfluence of light the decomposition of the diazonium compound is composable diazonium compound incapable when decomposed of combining with a coupling agent to form a dyestuif, and accelerating material for said decomposition intimately associated with said diazonium compound, said accelerating material having a reducible substance in the form of a compound of a higher oxide of copper, and a. combustion agent therefor, the combination of diazonium compound, reducible substance, and combustion substance being such that under the influence of light the decomposition of the diazonium compound is hastened by the presence of a compound having a lower oxide form of the metal, and such that under the influence of light the combustion substance reduces the higher oxide form of said metal to the efiective lower oxide form. a

19. A light sensitive material containing a decomposable diazonium compound incapable when decomposed of combining with a coupling agent to form a dyestufl, and accelerating material for said decomposition intimately associated with said diazonium compound, said accelerating material having a reducible substance in the, form of a compound of a higher oxide of copper, and a combustion agent, therefor derived from the group consisting of oxalic acid, citric acid and tartaric acid, the combination of diazonium compound, reducible substance, -and combustion substance being such that nnder the influence of light the decomposition of the diazonium compound is hastened by the presence of a compound having a lower oxide form of the metal,

' composable diazonium compound incapable when decomposed of combining with a coupling agent to form a dyestufi, and accelerating material for said decomposition intimately associated with said diazonium compound, said accelerating material having a reducible substance in the form of a compound of a higher oxide of chromium, and a combustion agent therefor, the combination of diazonium compound, reducible substance,

and combustion substance being such that under the influence of light the decomposition of the I diazonium compound is hastened by the presence of a compound having a lower oxide form of the metal, and such that under the influence of light the combustion substance reduces the higher oxide form of said metal to the effective lower oxide form.

21. A light sensitive material containing a decomposable diazonium compound incapable when "decomposed of combining with a coupling agent to form a ,dyestufl', and accelerating material for said decomposition intimately associated with said diazonium compound, said accelerating material having a reducible substance in the form of 4 a compound of ahigher oxide of chromium, and a combustion agent therefor derived from the group consisting of oxalic acid, citric acid and tartaric acid, the combination of 'diazonium com- 22. The method of accelerating the decomposition of a diazonium compound which comprises .combining with the diazonium compound light sensitive material containing a mettgl compound of higher oxide form of the metal and a combus- 5 tion agent therefor, which material under the influence of light and in the presence of the diazonium compound is reactive to produce a compound of lower oxide form of the metal, and subjecting the mixture to the action of actinic light, whereby the lower oxide form promotes decomposition of the diazonium compound.

WALKER M. I-IINMAN. 

